Deep Image Rendering

The goal of Deep ImageRenders frames with multiple depth samples in addition to typical color and opacity channels. Rendering is to improve the compositing workflow by storing Z-depth with samples. It works best in scenarios where traditional compositing fails like masking out overlapping objects, working with images that have depth-of-field or motion blur, or compositing footage in rendered volumes.

Most major compositing applications now support deep image compositing. The disadvantage of deep image rendering is the large amounts of memory required to render and store deep images.

The standard output format is OpenEXR.


Note: Photoshop can read EXRAlso known as OpenEXR. This image file format was developed by Industrial Light & Magic and provides a High Dynamic Range image capable of storing deep image data on a frame-by-frame basis. files. GIMP (open source) needs a third-party plugin to be able to read .exr


What is a deep image?
Instead of having single RGBA values for a pixel, a deep image stores multiple RGBA channel values per pixel together with a front and back Z-depth (Z and ZBack channels respectively). This tuple (R, G, B, A, Z, ZBack) is called a deep sample. Deep samples come in two flavours: point samples which have only a front depth specified (more formally Z → = ZBack) and volume samples which have a front and a back depth (Z < ZBack). Hard surfaces visible through a pixel are point samples and visible volumes are (you guessed it) volume samples. From these samples, two functions can be calculated: A(Z) and C(Z) representing the alpha and color of the pixel not further away than Z. These two functions are the basis of depth compositing and allow to compose footage together at any distance Z instead of just composing image A over image B. (Please note, that these functions are calculated by the compositing application. Octane only calculates the samples). Of course, this is a very rough overview with a lot of hand waving. Get the bigger picture and a thorough explanation at the article called "The Art Of Deep Compositing" ( You can also refer to "Interpreting OpenEXR Deep Pixels" and "Theory of Deep Samples".